Photoluminescence, X-ray excited radioluminescence and photoelectron yield characteristics were studied in multicomponent GdGaYAG:Ce and GdGaLuAG:Ce garnet films grown by liquid phase epitaxy. Nonradiative energy transfer from Gd ³⁺ to activator Ce ³⁺ ions was evidenced. At low Gd doping, , two virtually independent emission centers coexist, which compete for intensity: Ce ³⁺ with fast 5d-4f emission and Gd ³⁺ with slow 4f-4f emission. At higher Gd concentrations, the Ce ³⁺ emission retrieves intensity due to the energy transferred from Gd ³⁺ donors. At Gd concentration ~ 50% and above, the Gd ³⁺ emission is suppressed due to energy migration and transfer to Ce ³⁺ centers. In these samples, the host emission is also completely quenched and the best scintillator performance is achieved. Contrary to melt-grown crystals, no positive role of Ga substitution was found in epitaxial films.

Liquid phase epitaxy grown ${\mathrm{Lu}}_3{\mathrm{Al}}_5{\mathrm{O}}_{12}:\mathrm{Ce}$ (LuAG:Ce) $20\mu \mathrm{m}$ thick films and plate cut from the bulk Czochralski-grown LuAG:Ce crystal were prepared for comparison of photoelectron yield (PhY) and PhY dependence on shaping time $(0.5–10\mu \mathrm{s})$ . ${}^{241}\mathrm{Am}$ ($\alpha$ particles) was used for excitation. At the $0.5\mu \mathrm{s}$ shaping time, the best film shows comparable PhY with the bulk sample. PhY of bulk material increases noticeably more with shaping time than that of the films. Energy resolution of films is better. Influence of ${\mathrm{Pb}}^{2+}$ contamination in the films (from the flux) and antisite ${\mathrm{Lu}}_{\mathrm{Al}}$ defect in bulk material is discussed.